This invention relates to reactive dyes having a bridging group between triazinylamino groups each attached to a chromophore.
GB-A-1283771 and EP-A-0625551 disclose respective general ranges of reactive dyes of the formula (A) 
where D is a chromophore (which in the case of GB-A-1283771 is specifically a naphthylazo-phenylene or -naphthalene containing at least 3 sulphonic acid groups and in the case of EP-A-0625551 is any of a wide range of chromophores), R is H or an optionally substituted C1-4 alkyl group and X specifically a linking group which, in the case of GB-A-1283771, is an aromatic group selected from phenylene, diphenylene and naphthalene nuclei, and in the case of EP-A-0625551 is an aliphatic linking group, the group xe2x80x94NHXNHxe2x80x94 forming a bridging group between receptive triazine nuclei. The dyes of GB-A-1283771 offer a degree of fixation over a wide range of liquor to goods ratios and provide shades of very good light fastness, while those of EP-A-0625551 show good fastness and build up properties.
JP-A-62-172062 discloses a wide range of dyestuffs in which chromophores are linked by the specific group 
wherein Y is hydrogen, halogen or alkyl and Z is the reactive group xe2x80x94CHxe2x95x90CH2 or xe2x80x94CH2CH2OSO3H.
One of many examples of dyes disclosed has the following formula 
In our WO-A-99/05224, we describe a range of dyes in which the bridging group is derived from an aminoalkyl piperazine, which dyes have the formula (B) 
wherein:
each of R1, R2, R3 and R4, independently, is H or an optionally substituted alkyl group;
each of X1 and X2, independently, is a labile atom or group;
each of x and y, independently, is 0 or 1 and at least one of x and y is 1;
each of a and b, independently, is 2 to 5;
z is zero or is 1 to 4; and
when each of x and y is 1, a greater than b;
the or each R5, independently, is alkyl; and
each of D1 and D2, independently, is a monoazo or polyazo chromophore, or a metallized derivative thereof.
We have found surprisingly that if, in dyes of the above formula (A), the chromophore D is a particular disazo dye, defined below, then such dyes, especially when used for exhaust dyeing of cellulosic materials, can exhibit excellent all-round fastness properties and build-up and compatibility with other dyes whose preferred exhaust temperature is 80xc2x0 C. or, more preferably, above.
Thus, according to one aspect, the invention provides a dye of the formula (I)
D1xe2x80x94Yxe2x80x94D2xe2x80x83xe2x80x83(I)
wherein each of D1 and D2 independently is a chromophore of the formula 
in which
X is fluorine, chlorine or optionally substituted pyridinium;
an SO3H is present in the 5- or 6-position (preferably the 6-position) of the naphthalene nucleus;
n is zero or 1 (preferably 1); and 
in which
Z is a C5-12 aliphatic or aromatic cyclic hydrocarbon group, optionally additionally containing at least one hetero atom selected from N, O and S and optionally substituted by at least one of C1-4 alkyl and SO3H (or a salt thereof); or
at least two said cyclic hydrocarbon groups linked together; or
a C1-15 alkylene or C2-15 alkenylene chain, which said chain
(a) optionally additionally contains, so as to be interrupted or terminated by, at least one of (1) at least one hetero atom selected from N, O and S and (2) at least one C5-12 aliphatic or aromatic cyclic hydrocarbon group, which said cyclic hydrocarbon group optionally additionally contains at least one hetero atom selected from N, O and S and is optionally substituted by at least one of C1-4 alkyl and SO3H (or a salt thereof); and
(b) is optionally substituted by C1-4 alkyl, hydroxy-C1-4 alkyl, amino-C1-4 alkyl, hydroxyl, carboxyl or amino, which amino group or moiety is optionally substituted by one or two C1-4 alkyl groups, or by a substituent group which, together with (i) one of R1, R2 and R3 (each defined below), (ii) the nitrogen atom to which R1, R2 or R3 is attached and (iii) a chain length of Z between the said nitrogen and the substituent group, forms a heterocyclic group; and
each of R1, R2 and R3, independently, is hydrogen, a C1-4 alkyl, hydroxy-C1-4 alkyl or amino-C1-4alkyl group or each of R1 and R2, together with the respective nitrogen atoms to which they are attached and the chain Z therebetween, forms a heterocyclic group or (as defined above) one of R1, R2 and R3, together with (i) the nitrogen atom to which it is attached, (ii) the said substituent group on the chain Z and (iii) the said chain length between the said nitrogen atom and the said substituent group, forms a heterocyclic group; and
Y is other than 
xe2x80x83(and preferably contains no reactive group); or a sulphonic acid salt of the said dye of the formula (I).
When X is a substituted pyridinium, preferred substituents are 3-carboxyl, 3-carbonamido and 4-carboxyl.
In one preferred range of dyes, Z is a C1-10 alkylene chain optionally substituted by at least one group selected from C1-4 alkyl, hydroxy and carboxyl. Such chains may be free from any hetero atom or may contain additionally at least one hetero atom selected from O and N. More preferably, the chain is a C2-8-alkylene chain which is unsubstituted or substituted by at least one group selected from methyl, hydroxy and carboxyl. Still more preferably the chain is of the formula
[CH2]x
wherein x is 2 or 3, which alkylene chain is unsubstituted or substituted by one or two methyl groups or a hydroxy or carboxyl group and each of R1, R2 and R3 independently is selected from hydrogen, C1-4 alkyl and hydroxyethyl.
Examples of the group Y in which Z is a C1-10 alkylene chain optionally substituted by at least one of C1-4 alkyl, hydroxy and carboxyl are HNC2H4NH; HNC3H6NH; HNC4H8NH; HNC5H10NH; HNC6H12NH; HNC8H16NH; HNC2H4N(CH3); HNC3H6N(CH3); HNC2H4N(C2H4OH); HNC2H4N(C3H6OH); HNC3H6N(C2H4OH); HNC2H4N(C2H5); HNC2H4N(n-C3H7); HNC3H6N(C2H5); HNC3H6N(n-C3H7); (H3C)NC2H4N(CH3); (H3C)NC3H6N(CH3); (H3C)NC2H4N(C2H5); HNC2H4NH[CH(CH3)2]; (H5C2)NC2H4N(C2H5); HNC2H4NH[CH(CH3) (C2H5)]; HNC2H4N(n-C4H9); HNC2H4N[CH2CH(CH3) (OH)]; HNCH(CH3)CH2NH; HNC(CH3)2CH2NH; HNCH2CH(OH)CH2NH; HNCH2C(CH3)2CH2NH; HNCH(C2H5)CH2NH; HNCH2CH(CH3)C3H6NH; HNCH2CH(CH3)N [CH(CH3)2]; NHCH2C(CH3)2CH[CH(CH3)2]NH; HNC2H4S and HNCH(CO2H)CH2S.
Examples of the group Y in which Z is a C1-10 alkylene chain additionally containing a hetero atom are HNC3H6N(CH3)C3H6NH; HNC2H4OC2H4OC2H4NH; and HNC2H4OC2H4NH.
The C1-10 alkylene chain of Z may additionally contain an aliphatic or aromatic ring structure and examples of the group Y in which Z is such a chain are: 
where n is 2 or 3, which is an example of the group Y in which Z is C1-10 alkylene chain interrupted by an aliphatic ring containing at least one hetero atom. Of these groups, 
are especially preferred.
Especially preferred examples of the group Y in which Z is a C1-10 alkylene chain are NHC2H4NH; NHC3H6NH; NHCH(CH3)CH2NH; NHC2H4N(CH3); NHC3H6N(CH3); NHCH2CH(OH)CH2NH; NHC2H4N(C2H4OH); NHC(CH3)2CH2NH; NHC3H6N(C2H4OH); NHC2H4S; NHC2H4N(C2H5), N(CH3)C2H4N(CH3); NHC3H6N(C3H7); N(C2H4OH)C2H4N(C2H4OH); HNCH(CO2H)CH2S; N[CH(CH3)2]CH(CH3)CH2NH; HNC6H12NH; HNC3H6N(CH3)C3H6NH; HNC2H4OC2H4NH; and HNC2H4OC2H4OC2H4NH.
In another preferred range of dyes, Z is a phenylene group, optionally substituted by a sulphonic acid group or one or more methyl group(s). Examples of the group Y in which Z is a phenylene group are: 
or mixtures thereof, for example, a mixture of 
In yet another preferred range of dyes Z is a C1-15 alkylene chain and is substituted by a substituent group, preferably a C1-10 alkylene group, which, together with (i) one of R1, R2 and R3, (ii) the nitrogen atom to which R1, R2 or R3 is attached and (iii) a chain length of Z between the said nitrogen atom and the substituent group, forms a heterocyclic group. More preferably, the C1-15 alkylene chain is interrupted by a nitrogen atom which carries the substituent group, for example, in the case where Y is an imino-C14 alkylpiperazinyl group. Examples of Y in which the group Z includes a heterocyclic ring formed in this manner are: 
In another preferred range of dyes, each of R1 and R2, together with the respective nitrogen atoms to which they are attached and the chain Z therebetween, form a heterocyclic group, more preferably a piperazine group.
A dye of the formula (I), given and defined above, can be prepared by a method aspect of the invention, which method comprises allowing at least one reactive disazo dye of the formula (II) 
wherein X and n are as defined above and X1 is a fluorine, chlorine or optionally substituted pyridinium group, to react with a diamine or thioamine of the formula 
wherein each of R1, R2, R3 and Z is as defined above, at a pH of from 7 to 10, in a proportional amount of two moles of reactive disazo dye (II) per mole of diamine or thioamine (III) or (IV). The reaction may take from 1-12 hours.
The reactive disazo dye of the above formula (II) can be prepared by reacting a disazo dye of the formula (V) 
with a triazine of the formula 
wherein each of X X1 and X2 independently is chlorine, fluorine or optionally substituted pyridinium.
The disazo dye of the formula (V) may be prepared by firstly diazotising 4-acetylamino-2-aminobenzene sulphonic acid and coupling in acid conditions (pH of 2) onto a hydroxynaphthylamine of the formula 
and secondly diazotising 2-aminonaphthalene-1,5-disulphonic acid and coupling in neutral conditions (pH of 7) onto the hydroxynaphthylamine. Thereafter, removal of the acetyl protecting group of the amino group meta to the azo linkage yields the disazo dye of the formula (V).
Although dye formulae have been shown in the form of their free acid in this specification, the invention also includes dyes and processes using dyes in the salt form, particularly their salts with alkali metals such as the potassium, sodium, lithium or mixed sodium/lithium salt.
The dyes may be used for dyeing, printing or ink-jet printing, for example, of textile materials and paper.
The process for colouration is preferably performed at a pH of 7.1 to 13, more preferably 10 to 12. pH levels above 7 can be achieved by performing the process for colouration in the presence of an acid-binding agent.
The substrate may be any of a textile material, leather, paper, hair or film, but is preferably a natural or artificial textile material containing amino or hydroxyl groups, for example textile material such as wool, silk, polyamides and modified polyacrylonitrile fibres, and more preferably a cellulosic textile material, especially cotton, viscose and regenerated cellulose, for example, that commercially available as Tencel. For this purpose the dyes can be applied to the textile materials at a pH above 7 by, for example, exhaust dyeing, padding or printing. Textile materials are coloured bright shades and possess good fastness to light and wet treatments such as washing.
The new dyes are particularly valuable for colouring cellulosic textile materials. For this purpose, the dyes are preferably applied to the cellulosic textile material at a pH above 7 in conjunction with a treatment with an acid-binding agent.
Preferred acid-binding agents include alkali metal carbonates, bicarbonates, hydroxides, metasilicates and mixtures thereof, for example, sodium bicarbonate, sodium carbonate, sodium metasilicate, sodium hydroxide and the corresponding potassium salts. The dyes benefit from excellent build-up and high fixation.
At least for cellulosic materials, dyeing may be carried out at a temperature of from 80 to 105xc2x0 C., preferably 85 to 95xc2x0 C., still more preferably at about 90xc2x0 C., a somewhat higher temperature as compared with dyeing carried out with conventional monochlorotriazine exhaust dyes which are generally dyed at temperatures of about 80xc2x0 C. By operating at this temperature, particularly improved migration is obtained.
The new dyes can be applied to textile materials containing amine groups, such as wool and polyamide textile materials, from a neutral to mildly alkaline dyebath. The dyeing process can be carried out at a constant or substantially constant pH, that is to say the pH of the dyebath remains constant or substantially constant during the dyeing process, or if desired the pH of the dyebath can be altered at any stage of the dyeing process.
The dyes may be in liquid or solid form, for example in granular or powdered form.
We find surprisingly that such dyes provide the following advantageous properties:
a) good all-round fastness;
b) exceptionally good build-up, especially at a dyeing temperature of 90xc2x0 C.;
c) very strong dyeing;
d) exceptionally good robustness to changes in dyeing conditions, especially temperature, pH and, in particular, dyebath liquor to substrate ratio, leading to overall excellent shade reproducibility;
e) good wash off;
f) good fixation;
g) good aqueous solubility; and
h) good compatibility with other dyes of this type.
Especially preferred embodiments of the invention will now be described in more detail with reference to the following Examples in which all parts and percentages are by weight unless otherwise stated. Although preparation and dyeing with any single dye is exemplified, particular advantages can be seen when dyeing with mixtures of dyes.